The present invention relates to a liquid crystal display device having liquid crystal sealed in a space secured between an array substrate and a filter substrate.
As FIGS. 7 and 8 show, a conventional liquid crystal display device 101 is provided with an array substrate 103 having display elements 102 (each composed of, for example, a thin-film transistor and a pixel electrode connected thereto) formed in a matrix-like array and a filter substrate 106 having an opposing electrode 105 (a transparent electrode made of ITO or the like) formed thereon with a color filter 104 and an insulating layer OC sandwiched in between. The opposing electrode 105 is, all around or at part of the periphery thereof, so formed as to cross and reach beyond a sealing member 107 provided between the two substrates 103 and 106, thereby forming a lead portion. Through this lead portion, the two substrates 103 and 106 are electrically connected together by a connecting member 109 outside the sealing member 107. The region enclosed by the sealing member 107 is filled with liquid crystal 108.
However, in this structure, where the opposing electrode 105 crosses the bonding surface of the sealing member 107 as described above, the sealing member 107 is kept in intimate contact with the opposing electrode 105. As a result, under the negative pressure applied when the liquid crystal 108 is injected, the adhesion between the filter substrate 106 and the sealing member 107 is insufficient, degrading the hermeticity of the liquid crystal display device 101. The factor that degrades the hermeticity between the filter substrate 106 and the sealing member 107 is either insufficient adhesion between the opposing electrode 105 and the sealing member 107 or insufficient adhesion between the opposing electrode 105 and the insulating layer OC laid thereunder. In particular, as multiple layer structure becomes increasingly common in that portion of the filter substrate 106 which serves as the base layer to which the sealing member 107 is bonded, the base layer portion tends to exhibit poorer adhesion. An object of the present invention is to increase adhesion between a sealing member and a filter substrate.
On the other hand, the color filter 104 provided on the filter substrate 106 are composed of color elements (R, G, and B) arranged in a known arrangement, such as a stripe arrangement, mosaic arrangement, or delta (triangular) arrangement. Whereas low-resolution products adopt a mosaic or delta arrangement, high-resolution products adopt a stripe arrangement.
FIG. 9 is a sectional view of the conventional liquid crystal display device 101, taken along the direction in which the stripes of the color filter 104 are arranged. As this figure shows, on a transparent substrate 110 (made of glass or the like) of the array substrate 103 are formed gate conductors 112 for scanning and source conductors (not shown) for signal transfer, and within the regions demarcated by those conductors are formed display elements 102 each composed of a thin-film transistor (not shown) and a pixel electrode 111 (a transparent electrode made of ITO or the like) connected thereto. The greater parts of the individual pixel electrodes 111 are located within the demarcated regions mentioned above, and are laid on a layer insulation film 116 composed of a single layer or multiple layers. The remaining parts of the individual pixel electrodes 111, however, are located out of the demarcated regions mentioned above, and are laid over the gate conductors 112 with the gate insulation film 116 sandwiched in between.
On a transparent substrate 114 (made of glass or the like) of the filter substrate 106 are formed the color filter 104 provided with R, G, and B color elements, light-shielding patches constituting a black matrix 104K, and the opposing electrode 105 covering all these. The color filter 104, adopting a stripe arrangement, have their constituent color elements arranged so as to form stripes of different colors; that is, color elements of an identical color are arranged along each of the source conductors for signal transfer on the black matrix 104K. As the figure shows, the color filter 104, having a stripe arrangement, is formed continuously so as to cover the black matrix 104K.
However, in this structure, where the color filter 104 covers the black matrix 104K completely as described above, on the surface of the color filter 104 are formed elevated portions C that project toward the gate conductors 112 and the source conductors. This makes it difficult to stably hold spacers (not shown) for securing cell gaps on the gate conductors 112 and the source conductors. Moreover, the presence of the elevated portions C shortens the distances from the opposing electrode 105 to the gate conductors 112 and the source conductors, and thereby contributes to the emergence of parasitic capacitance. Another object of the present invention is to stabilize cell gaps. Still another object of the present invention is to reduce the parasitic capacitance appearing between an opposing electrode and gate and source conductors.
To achieve the above objects, according to the present invention, a liquid crystal display device is provided with: an array substrate having display elements formed in a matrix-like array; a filter substrate having a color filter and an opposing electrode formed thereon; a sealing member laid in the shape of a loop between the array and filter substrates in peripheral portions thereof, liquid crystal sealed in the region enclosed by the sealing member; and a connecting member for electrically connecting the array and filter substrates together in the peripheral portions thereof outside the sealing member. Here, a black matrix made of a metal and constituting part of the color filter and the opposing electrode are electrically connected together, and the black matrix and the opposing electrode are both so formed as to reach the peripheral portion of the filter substrate. Moreover, a region that is not covered by the opposing electrode is secured in the shape of a loop on the black matrix. The sealing member is arranged in this loop-shaped region.
Preferably, the black matrix is so formed as to be kept in direct contact with the opposing electrode.
Preferably, the opposing electrode is formed on the black matrix in a peripheral portion thereof outside the sealing member.
Preferably, the array substrate has, in a portion thereof lying inside the peripheral portion thereof, demarcated regions demarcated by a plurality of scanning conductors and signal-transfer conductors, and the display elements are each composed of a transistor and a pixel electrode, and are arranged individually in the demarcated regions. Moreover, the black matrix has openings formed therein so as to correspond to the demarcated regions, and the color filter adopts a stripe arrangement in which the openings located along each signal-transfer conductor are covered with color elements of an identical color, with grooves formed at boundaries between color elements of an identical color so that the black matrix is exposed through the grooves.
Preferably, the array substrate has, in a portion thereof lying inside the peripheral portion thereof, demarcated regions demarcated by a plurality of scanning conductors and signal-transfer conductors, and the display elements are each composed of a transistor and a pixel electrode, and are arranged individually in the demarcated regions. Moreover, the transistors and the pixel electrodes are arranged directly on a transparent substrate of the array substrate.